A coaxial cable used in a transmission line responds as a “distributed” capacitance to the circuit feeding it. We have to calculate the capacitance of 1.00 km for a cable having an inner radius of 0.110 mm and an outer radius of 0.58 mm. We may assume that the space between the conductors is filled with polystyrene.

Solution:             Click For PDF Version

The capacitance of a coaxial cable of length L, inner radius a and outer radius b, and filled with material having dielectric constant is

Dielectric constant of polystyrene is

Therefore, the capacitance of the 1.00 km coaxial cable with dimensions

and

will be